If an image is used in the header, a caption text isn't rendered as footer text

FransBouma

So if you have: ```  ============= ... ``` 'Foobar' isn't showing as footer. If the image link is moved below `=========` it is.

FransBouma

Won't fix. With #84 now fixed, we can close this, as it's not necessary to define the image as a header to get toc entries.